For purposes of this rules set only, BattleTechnology is using the word 'cave' to specify a single big hole underground or in a mountain side, and 'cavern' to specify one of a series of linked big underground holes. These holes may be anything from too small to fit a 'Mech into to the size of a large city. All 'cave' conditions apply to 'caverns'. Some 'cavern' conditions do not apply to 'caves'. The first problem noticed by a novice cavefighter is that he or she has trouble seeing. There is no light source in most caves. Sensors become vital. Therefore 'Mechs taking sensor hits must roll 2 D6. On a roll of 9 or above, nonessential systems (for these conditions) are hit. 'Mechs adapted for underground fighting mount exterior floodlights as well as the normal sensor array. On a roll of 7-8, the exterior mounted floodlight is hit. You have no light source. If another 'Mech is in the cavern with you, the area is fairly well illuminated. If all 'Mechs in the area lose or turn out their lights, you are at -4 on targeting-tracking, which translates to -2 gunnery, -1 on your piloting. If all lights are out, proceed as for visual sensor loss below. On a roll of 5-6, corn gear is hit. You have no way of telling friend from foe except on visual or I/R signature. On a roll of 3-4 or below, visual tracking systems fail entirely. On a roll of 2, I/R will go out as well. Once visual is out, movement is done cautiously; anything above 1/4 speed (round up) requires a piloting roll. If visual and I/R are both out, gunnery rolls are allowed only upon a'Mech which has f ired upon anyone in the same turn, or on a'Mech which has fired and not subsequently moved. If both of these systems are out, a firing 'Mech missing its gunnery roll must roll again to see if it hits the nearest other 'Mech. After two 'non-essential' sensor hits, roll 1 D6 only and apply conditions as above. These conditions are cumulative. Rock is more dense than air. This give rise to several special situations. While it is possible to fire from cavern to cavern, it is not possible to fire unless the firing 'Mech has line- of-sight. Indirect fire conditions are so unlikely as to be ruled out entirely in unrefereed games. If this is a refereed game, referee may choose to allow indirect fire under certain circumstances. In addition, in 'cave' conditions, there is a single entrance to the outside. If the cave has less than a 3-hex passage to the entrance, then during the day a 'Mech from outside the cave may not fire from outside even if line of sight is clear. He cannot see the target inside a darkened area. The inside 'Mech may fire; he is firing from darkness to light so his target is illuminated for him. Roll 2 D6 again for radio communication through this rock. On a roll of 2-4, rock is of a composition which interferes with radio traffic.Secure tight-beam communication (as in hard to intercept traffic within lance only) is limited to line-of-sight as well. Ordinary radio communication may pass through up to four walls. From the second wall on, roll 2D6 whenever it is attempted. For communications passing through a second wall , a roll of 4 or better gets through; for transmissions through a third wall, a roll of 7 or better gets through; for transmissions passing through a fourth wall, a roll of 12 gets through. Beyond that number, no transmission is possible. (This rule postulates irregular formations, pocket spaces, etc.) The cavern walls are dense (Hardened) and may not be fired through. If a 'Mech fires into a cavern wall at pointblank range (as in a miss), he must roll on the appropriate hit location table for halt damage (even a laser weapon will create a rapidly-moving shower of hot rock fragments). Any 'Mech within a one-hex range makes this roll. A 'Mech may choose to do this deliberately, but he will suffer the appropriate damage. In 'low ceiling' areas, any movement which is performed in an arc, rising and then curving down, is severely limited. Missiles which have a minimum-range limit are arced- fire missiles; they will misfire on a roll of 9 or less, causing damage similar in location to death-from-above to the firing 'Mech. As jumping is an arced movement, the maximum jump possible is the ceiling level minus one in hexes; default number of 4 hexes jump where ceiling level is unspecified. Death-From-Above is not allowed under these conditions. It is possible to retreat offmap where the perimeter allows. 'Mechs which do so are considered to be in disorderly retreat, and may not reenter. Referee may wish to have retreating 'Mechs roll to see if they became lost in a maze of caverns. Back to BattleTechnology 15 Table of Contents Back to BattleTechnology List of Issues Back to MagWeb Magazine List © Copyright 1992 by Pacific Rim Publishing. This article appears in MagWeb.com (Magazine Web) on the Internet World Wide Web. Other military history articles and gaming articles are available at http://www.magweb.com